<html>
  <head>
    <script>
      function test(show) {
        var cdt = document.getElementById('cdt');
        var wv = document.getElementById('wv');
        wv.showDevTools(show, cdt);
      }
    </script>
  </head>
  <body>
    <webview id="wv" src="http://localhost:3000/cash.html" style="display:inline-block;width:100%;height:50%"></webview>
    <button onclick="test(true)">show</button>

    <webview id="cdt" src="about:blank" style="display:inline-block;width:100%;height:50%"></webview>
   
    <button onclick="test(true)">show</button>
  </body>
</html>